Key locking mechanism



Oct. 12, 1948. El B, JOHNSON 2,451,090

` KEY LOCKING MECHANISM Filed July 18, 1945 2 Sheets-Sheet l EDWARD onnson Wa mass:

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Patented Oct. l2, 1948 UNITED STATES PATENT OFFICE Claims.

This invention relates to key lockingmechanisms and moreparticularly to mechanisms for locking a partially depressed key of a calculating machine in that position whereby the operator by observation may detect the location of the `partially depressed key and rectify any error caused thereby.

In the operation of calculating machines, the operator will sometimes only partially depress a key thinking that this key was fully depressed to register in the machine. When this occurs the key returns to-normal and the operator is therefore not conscious of the error. There is thus no means of identifying where the error occurred.

It is the primary purpose of the present invention to provide a locking mechanism for the keys of a calculating machine whereby when a keyis only partially depressed, insufficient to register in the machine, the partially depressed key is held in the depressed position allowing the operator to observe the location of the key wherein the error occurred.

Another purpose oi the present invention is to provide a key locking mechanism whereby the partially depressed key must -be fully depressed to register in the machine before it will return to normal position level with the other keys of the keyboard.

An illustrative embodiment of the invention is shown in the accompanying drawings, in which: Fig. 1 is a vertical sectional view through the keyboard of a calculating machine showing a group of keys, one of which is partially depressed and locked in that position;

Fig. 2 is a vertical sectional view through the keyboard online 2-2 of Fig. 1;

Fig. 3 is a horizontal sectional View taken along line 3--3 of Fig. 4;

Fig. 4 is a view similar to Fig. 1 showing one of the keys further depressed; i

Fig. 5 is a similar view showing the key fully depressed for proper registration in the machine;

Fig. 6 is a similar view showing the position of the operating parts as the key is returning to normal position; vandk K y Z Fig. 'l is a similar View showing the key as it approaches rest or normal position.

Referring then to the drawings in which like parts of the mechanism are designated by the same numerals in the several views, a calculating machine is provided with a key plate I0 and with a key guide plate II in relative spaced and parallel relationship, which guide plate receives in openings I4 for vertical sliding movement, the Shanks I2 of the keys I3.

Means, not shown, are incorporated into the calculating machine which yieldably hold all the keys in normal extended position above the keyboard and brackets I5 are secured to the underside of the key plate I0 through which the spaced rods I6 extend.

The key locking mechanisms are all identical; therefore only one will be described. A latch block Il, having ears I8 and I9 and a latch dog forming an integral part thereof, is slidably mounted on rods l5 and a spring 2I is connected between'one of the brackets I5 and the ear I8 tending to move the' latch block away from the shank I2 of the key. A notch 22 in the shank I2 of key I3 latches over the latch dog 20 to prevent a partially depressed key from returning to normal.

A bell cranklever 23, having legs 24 and 25, is pivotally mounted in the bracket I5 and tension spring 26 is connected to the outer end of leg 24 and to bracket l5 tending to move lever 23 in a clockwise direction. A spring 29 extending between the outer end of leg 24 of the bell crank lever and a bracket 30 attached to the key guide plate tends to move the bell crank lever in a counterclockwise direction. Tension spring 21 is attached at one end to the outer end of lever 25 and at the other end to ear I9 of the latching block II which tends somewhat to pull the latching block toward the notched side of the key.

In normal rest position, spring 2l has a greater pull on the latching block I'I than does the spring 2l, causing latch block II to move away from the key shank I2. Also, the springs 26, 21 and 29 balance to hold the bell crank lever in the normal position as shown in the two outer positions in Fig. 1.

The lug 28 is secured tothe shank I2 of the key I3 and when the key is depressed the lug controls the leg 24, moving bell crank 23 in a counterclockwise direction. When this occurs, the pull of spring 2l on the latch block Il becomes greater than the pull of spring 2I thus moving the latch block toward the key shank causing the latch dog 20 to hook into notch 22, thus preventing the key from returning to normal position.

Operation In normal position, the keys of a calculating machine are al1 flush and in extended position above the keyboard as shown in the two outer positions in Fig.` 1. Should the operator only partially depress a key-which movement is not sufficient to register in the machine-the key will be locked in this partially depressed position as shown in the center position in Fig. 1.

In moving from normal position to such partially depressed position, the lug 28 makes contact with leg 24 of the bell crank lever and moves it in a counterclockwise direction. This rotation of the bell crank lever causes the tension on spring 2l to become greater than the tension on spring 2t', thus causing latching block l1 to move to the right whereby the. latch dog 29 will hook into notch 22 in the key shank l2. In this hooked position, the number of the key will not have reg,- istered and this key will therefore remain partially depressed until it is fully depressed to register the number and thereafter be releasedV to move t normal position.

In depressing the key from partially depressed locked position to fully depressed position and return to normal position, the mechanism moves to thevarious positions as shown in Figs. 4, 5, 6 and '7.

InFig. 4, the key is moving downwardly and lug 28v is holding bell crank lever 23 in its rotated position with the leg 24 about to snap free of the iniluence of lug 28. In this position, the spring 21 is-still pulling latch dog. 20 against the notched side of the key shank I2.

In Fig. 5, the key is fully depressed to register the number in the calculating machine with the bell crank lever free from lug 28 and the springs 25', 21 and 29 balancing to hold the bell crank in normal position. The tension of spring 21 on the latch block IT has become less than the tension of spring, 2l whereby the latch dog 20 has moved to the left out of contact with the key shank l2.

InFig. 6, the key is returning, upwardly toward" normal' position and. lug 28 hasmoved bell crank lever in a clockwise direction so that it may move past the leg 24' whereas in Fig. 7 the key has raised. to a position where. the leg 24 of bell crank lever 23 is about to move free oi.V the lug 28 after which the parts moveto normal or rest position as shown in Fig. 1.

It will thus be seen that the key locking mechanism for. calculating machines herein shown and described is adapted to hold down a partially depressedkey until it is fully depressed` for registration in the machine. thereby informing the operator of the location of the partiallydepressed key. and allowing the` operator to rectify the error.

It will be understood that while but one specic embodiment of the invention has been herein shown and described, certain details ofthe construction shown may be alteredor omitted without departing from the spirit of theV invention as the same is dened in the appended claims.

I claim:

l. In= a machine provided with akey having a shank, the key adapted toy register numerical data on. full depressionv thereof, the combination of` latch. means on the shank, a movable latch means adapted to engage the shank latch means to. hold the key. in. partially depressed position: and normally held yieldable out, of engagement with the shank latch means, means for yieldably moving said movable latch means into engagement with the shank latch means on partial depression of the key and means for rendering the last mentioned yieldable latch moving means inei'lective on full depression of the key.

2. In a machine provided with a key having a shank, the key adapted to register numerical data. on full depression thereof, a notch intheshank, a latch dog movable intothe notch to hold the key in partially depressed position, means for yieldably holding the dog out of engagement with the notch in the shank, means for yieldably movingthe dog into the notch on partial depression ofthe key and means for preventing the dog from entering the notch after full depression of the key.

3.V In a machine provided with a key having a shank, thekey adapted to register numerical data on fullV depression thereof, a notch in the shank, a latch dog movably mounted to engage the notch in the shank on partial depression of the key,

means for yieldably moving the dog into thenotch on partial depression of the key, a lever` pivotally mounted adjacent the shank opposite the latch dog, yieldable means extending betweenthe lever andi the movable dog, a lug on the shank adapted to coact with the lever, said lug engaging the lever on partial depression of the key thereby increasing the effectiveness of the second yielding means and the lever moving freel of the lug on full depression of the-key.

4. In a machine provided with a key adaptedto register numerical data on full depression thereof, the key having a shank, the combination ofv a notch in the side of the shank, a latch dog movable into and out of the notch, means for yieldably holding thedog out of engagement withV the notch, a bell crank pivotallyv mounted adjacent the shank and on the side opposite the dog, the shank having a lug extending outwardly therefrom, saidl bellc crank having a normally'v REFERENCES CITED' The following references are of record in the iile of this patent:

UNITED- STAI'ESS PATENTS Number Name Date 1,378,701 Lyle Mayv 17, 1921 1,791,265 Dame Feb. 3, 1931 1,866,950 Silver July 12, 1932 1,955,606 Pitman Apr. 1'7, 1934I` 2,224,203 Turck et al. Dec: 10, 1940V 

